ASTM B651-83(2024)
(Test Method)Standard Test Method for Measurement of Corrosion Sites in Nickel Plus Chromium or Copper Plus Nickel Plus Chromium Electroplated Surfaces with Double-Beam Interference Microscope
Standard Test Method for Measurement of Corrosion Sites in Nickel Plus Chromium or Copper Plus Nickel Plus Chromium Electroplated Surfaces with Double-Beam Interference Microscope
SIGNIFICANCE AND USE
4.1 Different electroplating systems can be corroded under the same conditions for the same length of time. Differences in the average values of the radius or half-width or of penetration into an underlying metal layer are significant measures of the relative corrosion resistance of the systems. Thus, if the pit radii are substantially higher on samples with a given electroplating system, when compared to other systems, a tendency for earlier failure of the former by formation of visible pits is indicated. If penetration into the semi-bright nickel layer is substantially higher, a tendency for earlier failure by corrosion of basis metal is evident.
SCOPE
1.1 This test method provides a means for measuring the average dimensions and number of corrosion sites in an electroplated decorative nickel plus chromium or copper plus nickel plus chromium coating on steel after the coating has been subjected to corrosion tests. This test method is useful for comparing the relative corrosion resistances of different electroplating systems and for comparing the relative corrosivities of different corrosive environments. The numbers and sizes of corrosion sites are related to deterioration of appearance. Penetration of the electroplated coatings leads to appearance of basis metal corrosion products.
1.2 The values stated in SI units are to be regarded as the standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B651 − 83 (Reapproved 2024)
Standard Test Method for
Measurement of Corrosion Sites in Nickel Plus Chromium
or Copper Plus Nickel Plus Chromium Electroplated
Surfaces with Double-Beam Interference Microscope
This standard is issued under the fixed designation B651; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Summary of Test Method
1.1 This test method provides a means for measuring the
3.1 The depths and diameter of corrosion pits or the widths
average dimensions and number of corrosion sites in an
of corrosion crevices, and the number of pits per square
electroplated decorative nickel plus chromium or copper plus
millimetre or crevices per linear millimetre on a specimen
nickel plus chromium coating on steel after the coating has
surface, are determined using optical aids (magnifier,
been subjected to corrosion tests. This test method is useful for
microscope, and interference microscope). The values are
comparing the relative corrosion resistances of different elec-
compared to dimensions and numbers of corrosion sites
troplating systems and for comparing the relative corrosivities
obtained from other specimens.
of different corrosive environments. The numbers and sizes of
corrosion sites are related to deterioration of appearance.
4. Significance and Use
Penetration of the electroplated coatings leads to appearance of
basis metal corrosion products. 4.1 Different electroplating systems can be corroded under
the same conditions for the same length of time. Differences in
1.2 The values stated in SI units are to be regarded as the
the average values of the radius or half-width or of penetration
standard.
into an underlying metal layer are significant measures of the
1.3 This standard does not purport to address all of the
relative corrosion resistance of the systems. Thus, if the pit
safety concerns, if any, associated with its use. It is the
radii are substantially higher on samples with a given electro-
responsibility of the user of this standard to establish appro-
plating system, when compared to other systems, a tendency
priate safety, health, and environmental practices and deter-
for earlier failure of the former by formation of visible pits is
mine the applicability of regulatory limitations prior to use.
indicated. If penetration into the semi-bright nickel layer is
1.4 This international standard was developed in accor-
substantially higher, a tendency for earlier failure by corrosion
dance with internationally recognized principles on standard-
of basis metal is evident.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
5. Apparatus
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
5.1 Double-Beam Interference Microscope (lateral magnifi-
cation about 100×), capable of producing, with white light, a
2. Referenced Documents
visible group of interference fringes, and equipped with a
2.1 ASTM Standards:
calibrated fine focus and a graduated bifilar (movable cross
B487 Test Method for Measurement of Metal and Oxide
hair) eyepiece.
Coating Thickness by Microscopical Examination of
5.2 Magnifier or Microscope (10× to 20×), with light
Cross Section
source.
5.3 Rule, graduated in millimetres, and a scriber for pro-
This test method is under the jurisdiction of ASTM Committee B08 on Metallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.05 on
ducing visible lines on the specimen surface.
Decorative Coatings.
Current edition approved May 1, 2024. Published May 2024. Originally
5.4 Microscope, with a magnification capability of 500×,
approved in 1978. Last previous edition approved in 2019 as B651 – 83 (2019).
equipped with a bifilar eyepiece, for making measurements on
DOI: 10.1520/B0651-83R24.
2 opaque surfaces.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.5 Equipment for mounting and polishing of specimens for
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. microscopical cross-sectional measurements.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B651 − 83 (2024)
6. Specimen Preparation 7.1.2 For surfaces where the number of pits is less than
about 1000/cm , lightly scribe lines 10 mm or less apart to
6.1 Clean the corroded specimen surface with an agent or
form a rectilinear grid on the surface. Count the number of pits
agents that remove soil and corrosion products, but do not
within a scribed area, by using the magnifier, or the 100×
significantly change the surface of the corrosion sites. Scouring
microscope, whichever has the necessary resolution to assure
powder may be used to remove insoluble corrosion products,
pit identification. Determine the area that contains about 100
organic solvent to remove road tar, water accompanied by
pits, or, if the area exceeds 25 cm , count the number of pits in
gentle abrasion with a cloth to remove lightly adherent soil, etc.
a 25 cm area.
6.2 Mask with paint or tape that portion of the specimen
7.1.3 For surfaces with more than about five cracks per
surface on which no measurements of pits or cracks will be
millimetre, count the number of cracks on the surface image
made. Alternatively, a gasketed cell pressed onto the surface
that cross a 100× microscope reticle line of known length.
may be used. The opening in the gasket will define the area to
7.1.4 For a surface with fewer than about five cracks per
be stripped.
millimetre, lightly scribe a straight line up to 50 mm long on
the specimen surface. Using a magnifier or, if necessary, a
NOTE 1—If pitted, the area selected for measurement should contain at
least 100 pits or be as large as 50 mm by 50 mm. If the area contains
100× microscope, count the number of cracks in a known
cracks, the location for measurement should contain at least 100 cracks, or
length of line, or all the cracks in 50 mm length, whichever
be at least 50 mm long.
comes first.
6.3 Strip the chromium anodically at 6 V to 8 V in a solution
NOTE 3—If the cracks tend to be oriented, scribe the line approximately
containing about 50 g ⁄L of sodium carbonate (Na CO ).
2 3
perpendicular to the predominant crack direction.
6.4 Remove masking material, if desired.
7.2 Calculate the number of pits as pits per square
millimetre, or the number of cracks as cracks per millimetre.
NOTE 2—If tape was employed for masking, its removal is recom-
mended. When the specimen rests on tape, it will allow the specimen to Enter result in Table 1 under “pit density” or “crack density.”
settle slowly. This gradual movement interferes with measurements of
8. Determination of Mean Dimensions of Pits or Cracks
penetration with the interference microscope.
8.1 Observe one pit or crack wit
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.